Terminal connector for connecting an electrochemical cell to a medical device

ABSTRACT

A electrical connector for connection to an electrochemical cell is described. The connector comprises a conductive lid; a ferrule disposed within an opening through the conductive lid; a conductive center pin disposed within the ferrule; and a hermetic seal formed between the pin and an interior surface of the ferrule. A mating terminal connector adapted to be connected to the ferrule and the conductive center pin is further provided. The terminal connector is a device for easily and quickly connecting the cell to a circuit board of the kind found in an implantable medical device, such as a cardiac pacemaker, defibrillator, neuro-stimulator, drug pump, and the like.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a terminal connector orconnector assembly for connection to an electrochemical cell. Moreparticularly, the present invention relates in one embodiment to aterminal connector for attaining a simple, reliable connection of adevice to a high capacity, high energy density cell used in implantablemedical devices. The terminal connector connects to the cell's terminalassembly disposed on the exterior of the cell. That way, the terminalassembly occupies very little of the internal volume of the cell.

2. Description of Related Art

A case-grounded implantable electrochemical cell most commonly providestwo terminals of opposed polarity for connection of the cell to a deviceto be powered. One terminal extends from a glass-to-metal seal, and theother terminal extends from the case. Prior art terminals aredisadvantageous in that one of the terminals typically protrudesinwardly into the cell casing, thereby reducing the casing volumeavailable for containing the active cell materials. The use of prior artterminals thus results in a reduction of the overall cell volumetricefficiency. Additionally, the connection of the cell terminals to thedevice to be powered is typically accomplished by soldering, welding, orwire-bonding the cell terminals to the device.

For both the central terminal pin extending from the glass-to-metalseal, and the case grounding terminal that is welded or otherwise joinedto the cell casing, each is comprised of a fine wire extending outwardlyfrom the casing. These wires are fragile and are thus susceptible todisplacement and fracture by bending during cell handling. Additionally,it is difficult to position the terminal wires precisely and to maintainsuch positioning in the event they are to be matched with specificcorresponding terminals of the device to be powered by the cell whenmaking connection with such a device. The terminal wires are easily bentand misaligned during handling of the cell prior to connection to thedevice.

Heretofore, a number of patents and publications have disclosed cellsincluding terminal connections to powered devices. For example, U.S.Pat. No. 5,250,373 to Muffoletto et al., which is assigned to theassignee of the present invention and incorporated herein by reference,describes an electrochemical cell including a central lead that is fixedrelative to a lid by a generally cylindrical ferrule element, which isfitted at one end to an opening in the lid and secured to the lid bywelding. The space between the lead and the ferrule is filled by a glassseal that extends along the major portion of the length of the ferrule.This glass-to-metal seal insulates the lead electrically from the lidand the cell casing, and seals the lead so that no egress or ingress ofgases or liquids into or out of the casing can occur. The entireglass-to-metal seal is disposed beneath the lid on the interior of thecell casing. This assembly thus occupies space within the cell casingthat could be more advantageously used for active materials, which wouldincrease the cell's volumetric efficiency and capacity.

Additionally, U.S. Pat. No. 6,004,692 to Muffoletto et al., which isassigned to the assignee of the present invention and incorporatedherein by reference, describes an electrochemical cell including anelectrode assembly constructed of a serpentine electrode withinterleaved counter electrode plates. The electrochemical cell disclosedtherein also includes a glass-to-metal seal assembly similar to thatdisclosed in the aforementioned U.S. Pat. No. 5,250,373 to Muffoletto etal., wherein the lead is connected to the interleaved cathode plates bya cathode bridge. These are only two examples of many conventionallyconstructed electrochemical cells having the glass-to-metal sealassembly disposed beneath the lid on the interior of the casing, thususing space within the cell that could be more advantageously used foractive materials.

SUMMARY OF THE INVENTION

There is therefore a need for an electrical terminal connector forattaining a simple, reliable connection to the terminal assembly of ahigh capacity, high energy density cell used in implantable medicaldevices, wherein the terminal assembly is exterior of the cell, andoccupies very little, if any, of the valuable internal volume of thecell that is better used to contain active materials.

Accordingly, embodiments of the present invention are provided that meetat least one or more of the following objects of the present invention.

It is an object of this invention to provide a cell for use in animplantable medical device that includes a terminal assembly that isexternal to the cell casing.

It is a further object of this invention to provide a cell that includesa terminal assembly that is simple to connect to and disconnect from aterminal connector connectable to an implantable medical device.

It is a further object of this invention to provide a cell forconnection to a device that includes a terminal connector that is simpleto connect to a circuit board of the device.

It is a further object of this invention to provide a cell for use in animplantable medical device that includes a terminal connector that isconnectable to a corresponding mating fitting of the device, wherein themating fitting is a standardized, mass-produced fitting.

According to the present invention, therefore, a terminal connector isprovided for connection to a cell. The cell includes a conductive lidcomprised of a wall having an inside surface, an outside surface, and anopening therethrough from the inside surface to the outside surface. Thecell comprises a ferrule of a conductive hollow cylindrical body havinga central axis, an interior surface, an exterior surface, an outer end,and an inner end. The inner end is electrically joined and sealed withinthe opening through the wall of the conductive lid and is substantiallycoplanar with the inside surface of the wall of the conductive lid; thecell further includes a conductive center pin or terminal pin comprisingan elongated surface, an inner end, and an outer end. The terminal pinis disposed within the hollow cylindrical body of the ferrule andaligned along the central axis thereof, thereby forming an annularcavity between the elongated surface of the terminal pin and theinterior surface of the ferrule. A hermetic glass-to-metal seal isformed in the annular cavity.

The inner end of the ferrule is preferably joined to the lid by a seamweld that is flush with the inside surface of the lid. The exteriorsurface of the ferrule may be threaded to enable connection with acorrespondingly threaded terminal connector of the present invention.Alternatively, the exterior surface of the ferrule may be provided withsmall protruding pins to enable connection with a BNC terminal connectorof the present invention. The conductive lid, the ferrule, and thecenter pin may be made of titanium, or of stainless steel. In the latterinstance, the terminal pin may be made of molybdenum.

Also according to the present invention, a terminal connector isprovided for connection to the ferrule electrically joined to the casingand for connection to the insulated conductive terminal pin. Theterminal connector comprises a non-conductive cap including a hollowcylindrical body covered at an outer end by a flange, a center terminalembedded in the flange, and a perimeter terminal disposed within thehollow cylindrical body of the cap. When the terminal connector isconnected to the ferrule, the exterior surface of the ferrule is incontact with the perimeter terminal of the terminal connector, and thecell's terminal pin is in contact with the center terminal of theterminal connector. This provides opposite polarity electricalconduction through the terminal pin and through the body of the ferrule.

If the exterior surface of the ferrule is threaded, the perimeterterminal of the terminal connector is correspondingly threaded to enablea threaded connection between the terminal connector and the ferrule. Ifthe exterior surface of the ferrule is provided with small protrudingpins, the terminal connector is formed as a BNC connector adapted toengage with the protruding pins of the ferrule. If the exterior surfaceof the ferrule is provided with a smooth cylindrical surface, theperimeter terminal of the terminal connector is provided with a smoothinner surface dimensioned such that the terminal connector ispress-fittingly engageable with the exterior surface of the ferrule. Ifa permanent, rather than detachable electrical connection between theferrule and the terminal connector is desired, the perimeter terminal ofthe terminal connector may be joined to the exterior surface of theferrule by a weld. In this embodiment, a cap of the terminal connectoris preferably made of a ceramic material rather than a plastic, in orderto prevent damage to the cap during the welding process.

To facilitate connection of the terminal connector to an external deviceto be powered by the cell, the terminal connector preferably furthercomprises a first conductor extending from the center terminal through aflange of the cap, and a second conductor extending from the perimeterterminal through the cap flange. In one preferred embodiment, the firstand second conductors are comprised of elongated tabs adapted forconnection into an electrical receptacle. The electrical receptacletypically is comprised of a pair of slots in a circuit board dimensionedto permit the elongated tabs of the conductors to be “plugged” intothem. The center contact, the perimeter contact, and the electricalconductor of the terminal connector may be made of stainless steel ortitanium.

Also according to the present invention, an electrochemical cell isprovided comprising a conductive casing closed at one end and having anopening at the opposite end thereof closed by a conductive lid, theconductive lid is comprised of a wall having an inside surface, anoutside surface, and an opening therethrough from the inside surface tothe outside surface; an electrode assembly housed inside the casing andcomprised of a first electrode of a first polarity and including acurrent collector; a second electrode of a second, opposite polarity; anelectrolyte provided in the casing to activate the electrode assembly; aferrule comprised of a conductive hollow cylindrical body having acentral axis, an interior surface, an exterior surface, an outer end,and an inner end, the inner end electrically joined and sealed withinthe opening through the wall of the conductive lid and beingsubstantially coplanar with the inside surface of the wall of theconductive lid; a conductive center terminal pin comprising an elongatedsurface, an inner end electrically connected to the current collector,and an outer end, the terminal pin disposed within the hollowcylindrical body of the ferrule and aligned along the central axisthereof, thereby forming an annular cavity between the elongated surfaceof the terminal pin and the interior surface of the ferrule; and ahermetic seal formed in the annular cavity. The electrochemical cell mayfurther include the aforementioned terminal connector.

The electrochemical cell may be configured with a case-negative orcase-positive ground configuration, the former being preferred. Thecase-negative cell may be comprised of a simple rectilinear electrodestructure, or the electrodes may be configured in a serpentine orjellyroll arrangement. In the serpentine arrangement, the cell mayfurther comprise a cathode bridge to facilitate connection of a currentcollector to the multiple cathode plates interleaved between the foldsof the serpentine anode.

The terminal connectors of the present invention are advantageousbecause they provide a simple, reliable connection to high capacity,high energy density electrochemical cells, such as e.g., those used inimplantable medical devices. The terminal connectors of the presentinvention are connectable to terminal assemblies disposed on theexterior of the cell. Electrochemical cells using the terminalconnectors of the present invention can therefore contain a greateramount of active materials, thereby increasing the incapacity and energydensity.

The foregoing and additional objects, advantages, and characterizingfeatures of the present invention will become increasingly more apparentupon a reading of the following detailed description together with theincluded drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described by reference to the followingdrawings, in which like numerals refer to like elements, and in which:

FIG. 1 is a perspective view of one electrochemical cell including acell terminal assembly and a mating terminal connector of the presentinvention separated from the cell's terminals;

FIG. 2 is a perspective view of the cell mated to the terminal connectorof FIG. 1;

FIG. 3 is a side cross-sectional view of the cell's terminal assemblytaken along line 3-3 of FIG. 1;

FIG. 4 is a side cross-sectional view taken along line 4-4 of FIG. 2showing the cell's terminal assembly mated to the terminal connector;

FIG. 4A is a side cross-sectional view of a cell that is an alternativeto the cell of FIG. 4, the cell including a terminal assembly mated tothe terminal connector depicted also in FIG. 4;

FIG. 5 is a top view of the terminal connector of FIGS. 1, 2, 4, and 4A,depicting conductors provided for connection to a device to be poweredby an electrochemical cell;

FIG. 6 is a side cross-sectional view of the terminal connector of FIG.2 and FIG. 5, taken along line 6-6 of FIG. 5;

FIG. 7 is a side cross-sectional view of a first alternative embodimentof the terminal connector of the present invention connected by a pressfit to a cell's terminal assembly;

FIG. 8 is a side cross-sectional view of a second alternative embodimentof a terminal connector of the present invention connected by welding toa cell's terminal assembly;

FIG. 9 is a side cross-sectional view of a third alternative embodimentof a terminal connector of the present invention using a BNCconfiguration connected to a cell's terminal assembly; and

FIGS. 10A-10C are detailed side elevation views of the engagement meansfor securing the mating terminal connector of FIG. 9 to the cell'sterminal assembly.

The present invention will be described in connection with a preferredembodiment, however, it will be understood that there is no intent tolimit the invention to the embodiment described. On the contrary, theintent is to cover all alternatives, modifications, and equivalents asmay be included within the spirit and scope of the invention as definedby the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

For a general understanding of the present invention, reference is madeto the drawings. In the drawings, like reference numerals have been usedthroughout to designate identical elements. In describing the presentinvention, a variety of terms are used in the description.

As used herein, the term “active material” is meant to indicate acathode or anode material used in an electrochemical cell, whichparticipates in the oxidation-reduction reaction(s) therein, therebyresulting in the discharge of energy from the electrochemical cell.

The present invention provides a direct and simple means of connecting acell to a device. The present invention adapts the terminal feed-throughsystem that is used in case-grounded implantable grade cells. Thatsystem includes a glass-to-metal seal comprising a cylindrical metalferrule, a non-conductive hermetic sealing material, and a centralizedterminal pin. The pin and ferrule are of opposed polarity and areelectrically insulated from one another with the hermetic sealingmaterial. The seal also holds the terminal pin concentric with theferrule and hermetically separates the internal cell components fromtheir outside environment. Typically, the ferrule is contained withinthe cell body, and cannot be used as a terminal circuit connector.

In that respect, the cell's terminal assembly is characterized by acylindrical metal ferrule that protrudes from the outer surface of thecasing, and the cell lid in particular. The ferrule is made of the sameconductive material as the casing and lid to which it is joined. Theterminal assembly is configured to accept a mating terminal connectorconnected to the circuitry of the device to be powered by the cell. Theferrule of the cell's terminal assembly thus eliminates the need toprovide a second terminal pin extending from the cell lid or casing.

The outer and inner geometry of the ferrule may be threaded or straightwalled, but must correspond with the configuration of the matingterminal connector connectable to the device to be powered. The ferrulemay be configured for a mechanical connection (e.g., a press-fit, athreaded, of a BNC-type connection), or a soldered, brazed, or weldedconnection.

FIG. 1 is a perspective view of one electrochemical cell including acell terminal assembly and a mating terminal connector. FIG. 2 is aperspective view of the cell and mating terminal connector of FIG. 1,wherein the mating terminal connector is shown connected to the cell.Cell 10 is comprised of a conductive casing 12 closed at lower end 14,and having walls 16 and 17, and an opening 19 at the upper end 18thereof. The casing 12 is closed at opening 19 by a conductive lid 20,which is sealed to casing 12 by suitable means such as e.g. seam weld 15(see FIG. 3). Cell 10 further comprises an electrode assembly housedinside casing 12 and comprised of a first electrode of a first polarityincluding a current collector 40, a second electrode of a second,opposite polarity (not shown), and an electrolyte (not shown) providedin the casing 12 to activate the electrode assembly.

FIG. 3 is a side cross-sectional view of the cell terminal assemblytaken along line 3-3 of FIG. 1. The terminal assembly 100 comprises aferrule 110 comprised of a conductive hollow cylindrical body 112 havinga central axis 199, an interior surface 114, an exterior surface 116, anouter end 118, and an inner end 119, the inner end 119 electricallyjoined and sealed within an opening 22 through the wall 24 of theconductive lid 20 and substantially coplanar with the inside surface 26of the lid wall 24. The coaxial connector assembly 100 further comprisesa conductive terminal pin 130 comprising an elongated surface 132, aninner end 134, and an outer end 136. The pin 130 is disposed within thehollow cylindrical body 112 of the ferrule 110 and aligned along thecentral axis 199 thereof, thereby forming an annular cavity 129 betweenthe elongated surface 132 of the terminal pin 130 and the interiorsurface 114 of the ferrule 110. Ferrule 110 and center pin 130 are thuscoaxial, sharing a common central axis 199.

Coaxial connector assembly 100 further comprises a hermetic sealingmaterial 140 disposed in the annular cavity 129 to form a glass-to-metalseal (GMTS) with the ferrule 110 and terminal pin 130. As used herein, aGMTS is to be considered as being completely impervious to the passageof liquid or gas either into or out of the cell, and completelyresistant to corrosion or other degradation by materials within thecell, or in the external environment. The sealing material 140 is formedof electrically insulative material, so that terminal pin 130 iselectrically insulated from ferrule 110. In one preferred embodiment,the sealing material 140 is a glass seal, such as is described and shownin the aforementioned U.S. Pat. No. 5,250,373 to Muffoletto et al.

The inner end 119 of ferrule 110 is preferably joined to lid 20 by aperipheral seam weld 29 that is flush with the inside surface 26 of thelid 20. Ferrule 110 is thus electrically connected and sealed to lid 20.

Terminal pin 130 is electrically connected to one of the electrodes ofcell 10. In the embodiment depicted in FIG. 3, terminal pin 130 extendsdownwardly into the cell 10, and terminal pin 130 is joined to acoupling element 42 extending from the current collector 40 by suitablemeans such as e.g., welding. In other embodiments, the coupling element42 of current collector 40 may be formed as a hollow sleeve, and theinner end 134 of terminal pin 130 may be roughened and fitted within asleeve, as is shown and described in the aforementioned U.S. Pat. No.6,929,881 to Wutz et al.

It is preferable that the conductive materials of connector assembly 100are made of the same material as the lid 20. In one embodiment in whichlid 20 is made of titanium, ferrule 110 and center pin 130 are also madeof titanium. In another embodiment in which lid 20 is made of stainlesssteel, ferrule 110 is made of stainless steel. In this embodimentterminal pin 130 may also made of stainless steel, or molybdenum. It isto be understood that these materials are to be considered exemplary,and not limiting, and that other suitable metallic materials may be usedthat are formable to precise dimensions and resistant to degradation bymaterials within the cell and/or materials in the external environment.

FIG. 4 is a side cross-sectional view of the cell's terminal assembly100 connected to the mating terminal connector 200. The mating terminalconnector 200 is adapted to be connected to coaxial connector assembly100, and more specifically, the ferrule 110 and the conductive centerpin 130 thereof. Terminal connector 200 is comprised of a non-conductivecap 210 including a hollow cylindrical body 212 covered at an outer end214 by a flange 216, a center terminal 220 embedded in the flange 216,and a perimeter terminal 230 disposed within the hollow cylindrical body212 of the cap 210. When the mating terminal connector 200 is connectedto the ferrule 110, the exterior surface 116 of the ferrule 110 isbrought into contact with the perimeter terminal 230 and the terminalpin 130 is brought into contact with the center terminal 220, therebyenabling electrical conduction from the cell 10 through the centerterminal pin 130 and through the body 112 of the ferrule 110.

In one embodiment depicted in FIGS. 3, 4, and 4A, the exterior surface116 of the ferrule 110 is provided with threads 122 and the inside ofthe hollow cylindrical body 212 of the mating terminal connector iscorrespondingly provided with matching threads 232 to enable a threadedconnection between the terminal connector 200 and the ferrule 110.

In another embodiment, the ferrule is formed as the male fitting of aBayonet Neill Concelman connector. Such a connector, also known as a BNCconnector, is a standard industrial electrical connector often used inthe transmission of high fidelity electrical signals, such as radiofrequency signals. The BNC connector is a type of bayonet connector,named after the resemblance to the standard twist-on attachment for abayonet.

FIG. 9 is a side cross-sectional view of a BNC connector embodiment ofthe terminal connector of the present invention connected to acorresponding alternative BNC mating connector. FIGS. 10A-10C aredetailed side elevation views of the engagement of means for securingthe terminal connector 201 of FIG. 9 to the cell's terminal assembly101. The terminal assembly 101 is similar to the terminal assembly 100previously described herein and shown in FIGS. 3-4A, and is comprised offerrule 111, terminal pin 130, and hermetic sealing material 140.Ferrule 111 includes an exterior surface 116, an interior surface 114,an outer end 118, and an inner end 119. Mating terminal connector 201 issimilar to terminal connector 200 previously described herein and shownin FIG. 4, and is comprised of non-conductive cap 211 including a hollowcylindrical body 212 covered at an outer end 214 by a flange 216, acenter terminal 220 embedded in the flange 216 and a perimeter terminal231 disposed within the hollow cylindrical body 212 of the cap 211.

In lieu of threads 122 as shown on ferrule 110 of the terminal assembly100 of FIG. 3, ferrule 111 is provided with a smooth exterior surface116, from which protrudes a first pin 124 and a second pin 126, spacedat about 180 degrees opposite each other. When the terminal connector201 is first brought into contact with the cell's terminal assembly 101,pin 124 is separated slightly from an engagement latch 233 formed on theinner surface 234 of perimeter terminal 231, as shown in FIG. 10A. Atwisting motion of the terminal connector 201 relative to terminalconnector 101 is performed, as indicated by arrows 99 and 98, causingpin 124 and engagement latch 233 to approach each other as indicated byarrows 97 and 96. When pin 124 makes contact with engagement latch 233as indicated in FIG. 10B, the tang 235 is displaced diagonally upwardlyrelative to pin 124 as indicated by arrows 95 and 94. When pin 124reaches slot 236, pin 124 pops into slot 236 as indicated by arrow 93 inFIG. 10C, and pin 124 is engaged with tang 235 of engagement latch 233.In a like manner, a similar engagement latch (not shown) is provided onthe inner surface 234 of perimeter terminal 231 about 180 degreesopposite latch 233 for engagement with pin 126 of ferrule 111 of theterminal connector 101.

Referring again to FIG. 10C, in an alternative embodiment of the BNCconnector configuration, perimeter terminal 231 is provided with a pairof slots such as slot 237 with which pins 124 and 126 are engaged. Sucha slotted configuration is commonly used in the female BNC connectorssuch as mating terminal connector 201.

Referring again to FIG. 9, for either configuration of the BNC connectorassembly, the mating terminal connector 201 is preferably provided withan elastomeric flat washer 219, which provides an axial force that helpsto secure connector 201 to the terminal assembly 101. When matingterminal connector 201 is brought into contact with the cell's terminalassembly 101 and twisted in the previously described joining motion,elastomeric washer 219 is compressed. When the mating terminal connector201 is fully engaged with the cell's terminal assembly 101 by the actionof engagement latches or slots with pins 124 and 126, elastomeric washer219 remains compressed, thereby providing axial biasing forces againstboth the mating terminal connector 201 and terminal assembly 101. Thebiasing force applied by the elastomeric washer 219 to the terminalconnector 201 is indicated by arrow 92, while the force applied by thewasher 219 against the cell's terminal assembly 101 is indicated byarrow 91. These forces serve to retain pins 124 and 126 securely in theengagement latches 235, or in the slots 237 provided in the perimeterterminal 231 of the mating connector. It will be apparent that themating terminal connector 201 is separable from the terminal assembly101 by the application of a compressive axial force upon washer 219, anda twisting motion applied to mating terminal connector 201 that isopposite to the twisting motion previously described.

In another embodiment of the present invention, the ferrule is providedwith a smooth cylindrical surface, and the perimeter terminal of theterminal connector is provided with a smooth inner surface dimensionedsuch that the mating connector is press-fittingly engageable with theexterior surface of the ferrule. FIG. 7 is a side cross-sectional viewof this alternative embodiment of the cell's terminal assembly connectedby a press fit to a corresponding alternative mating terminal connector.The cell's terminal assembly 102 is similar to the terminal assembly 100previously described herein and shown in FIGS. 3-4A, and is comprised offerrule 113, terminal pin 130, and hermetic sealing material 140.Ferrule 113 includes an exterior surface 116, an interior surface 114,an outer end 118, and an inner end 119. The terminal connector 202 issimilar to the terminal connector 200 previously described herein andshown in FIG. 4, and is comprised of non-conductive cap 210 including ahollow cylindrical body 212 covered at an outer end 214 by a flange 216,a center terminal 220 embedded in the flange 216 and a perimeterterminal 238 disposed within the hollow cylindrical body 212 of the cap210.

In lieu of threads 122 as shown on ferrule 110 of the terminal connector100 of FIG. 3, ferrule 113 of terminal assembly 102 of FIG. 7 isprovided with a smooth exterior surface 116. Mating terminal connector202 is provided with a corresponding smooth cylindrical interior surface239 that is slightly smaller in diameter than the diameter of surface116 of ferrule 113, such that the terminal connector 202 may be fittedto the cell's terminal assembly 102 by a mild press fit of ferrule 113within perimeter terminal 238. As used herein, a mild press fit is a fitbetween two parts that is achievable by the application of forces easilydelivered by a person's thumb and fingers. It will be apparent that theterminal connector 202 is separable from ferrule 113 by the applicationof similar forces applied in the opposite direction to those used in theconnection with the cell's terminal assembly.

If a permanent, rather than detachable electrical connection between theferrule and the terminal connector is desired, the perimeter terminal ofthe mating terminal connector may be joined to the exterior surface ofthe ferrule by welding, soldering, or brazing. FIG. 8 is a sidecross-sectional view of this alternative embodiment of the cell'sterminal assembly 103 connected by welding to a correspondingalternative mating terminal connector. The cell's terminal assembly 103is similar to the terminal assembly 102 previously described herein andshown in FIG. 7, and is comprised of ferrule 113, terminal pin 130, andhermetic sealing material 140. Ferrule 113 includes an exterior surface116, an interior surface 114, an outer end 118, and an inner end 119.Mating terminal connector 203 is similar to the terminal connector 202previously described herein and shown in FIG. 7, and is comprised ofnon-conductive cap 213 including a hollow cylindrical body 215 coveredat an outer end 217 by a flange 218, a center terminal 220 embedded inthe flange 218 and a perimeter terminal 240 disposed within the hollowcylindrical body 215 of the cap 213.

The mating terminal connector 203 is fitted to the cell's terminalassembly 103 by a mild press fit or a sliding fit between the interiorsurface 242 of perimeter terminal 240 and the exterior surface 116 offerrule 113. To effect the permanent attachment of the terminalconnector 203 to the cell's terminal assembly 103, a weld 243 is madewhich joins perimeter terminal 240 to ferrule 113. Weld 243 ispreferably a plug weld made within a hole 244 that is provided inperimeter terminal 240 prior to the assembly operation. In the preferredembodiment, an additional plug weld 246 is made at a location 180degrees around perimeter terminal 240; and additional plug welds (notshown) are made at equally spaced locations, such a e.g., four weldsspaced at 90 degree intervals.

In the embodiment depicted in FIG. 8, the cap 213 of the terminalconnector 203 is preferably made of a ceramic material rather than aplastic, in order to prevent melting, decomposition or other thermaldamage to cap 213 during the welding process. Suitable ceramic materialsinclude, but are not limited to alumina, titania, zirconia, siliconnitride, and silicon carbide.

Each of the terminal assemblies and mating terminal connectors depictedin FIGS. 4, 7, 8, and 9 are dimensioned to ensure that an effectiveelectrical contact (i.e. one essentially of zero resistance) is madebetween the cell's terminal pin and the center terminal of the matingterminal connector, and between the cell's ferrule and the perimeterterminal of the terminal connector. For the contact between the cellferrule and the perimeter terminal of the mating terminal connector, foreach of the embodiments depicted in FIGS. 4, 7, 8, and 9, such effectiveelectrical contact is easily ensured, by virtue of the extensiveengagement of the respective surfaces with each other.

In the embodiment 150 of FIG. 4, threads 232 of the mating terminalconnector 200 make firm and extensive contact with threads 122 offerrule 110. In the embodiment of FIG. 7, interior surface 239 ofperimeter terminal 238 of the mating terminal connector 202 makes firmand extensive contact with surface 116 of the cell's ferrule 113,particularly due to the press fit between ferrule 110 and perimeterterminal 238. In the embodiment of FIG. 8, interior surface 242 ofperimeter terminal 240 of the terminal connector 203 makes firm andextensive contact with surface 116 of the cell's ferrule 113,particularly due to the welds 243 and 246 between ferrule 113 andperimeter terminal 240. In the embodiment of FIG. 9, interior surface234 of perimeter terminal 231of the mating terminal connector 201makesfirm and extensive contact with surface 116 of the cell's ferrule 111,particularly due to engagement of pins 124 and 126 of ferrule 113 andthe engagement latches 235 or slots 237 of the perimeter terminal 231.

For the contact between the terminal pin 130 of the cell's terminalassembly and the center terminal 220 of the mating terminal connector,for each of the embodiments depicted in FIGS. 4, 7, 8, and 9, sucheffective electrical contact must be attained by proper dimensioning ofthe respective terminal assemblies and mating terminal connectors. Thispoint will be illustrated with reference to the embodiment of FIG. 4,but is equally applicable to those of FIGS. 7, 8, and 9.

Referring to FIG. 4, when the mating terminal connector 200 is fitted tothe cell's terminal assembly 100, center electrical contact 220 must bebrought into forced contact with outer end 136 of terminal pin 130, inorder to achieve effective electrical contact between these twoconductors. This is most simply accomplished by having outer end 136 ofterminal pin 130 function as a stop against center electrical contact220 of the mating terminal connector 200. In other words, when themating terminal connector 200 is fitted to the cell's terminal assembly100, it is the outer end 136 of the terminal pin 130 coming into contactwith center electrical contact 220 that stops the axial movement of theterminal connector 200 toward the cell's terminal assembly 100.

In one embodiment, center electrical contact 220 is made flush (i.e.coplanar) with inner surface 209 of flange 210 of the mating terminalconnector 200. In order for the outer end 136 of the terminal pin 130 toact as a stop against center electrical contact 220 of the matingterminal connector 200, outer end 136 of terminal pin 130 protrudesslightly beyond the plane defined by the end 118 of ferrule 100.Accordingly, when the terminal connector 200 is threadedly engaged withferrule 200, the rotation of mating connector 200 on ferrule 110 will bestopped because of contact between the outer end 136 of the terminal pin130 and center electrical contact 220 of the mating terminal connector200. A small additional tightening torque applied to the terminalconnector 200 will firmly force center electrical contact 220 againstthe end 136 of the terminal pin 130, thereby ensuring effectiveelectrical contact there between. In this embodiment, it is preferredthat the outer end 136 of the terminal pin 130 protrudes at least about0.020 inches beyond the plane defined by the end 118 of ferrule 100 inorder to provide effective electrical contact.

In another embodiment (not shown), the outer end 136 of the terminal pin130 may be recessed beneath the plane defined by the outer end 118 offerrule 110. In this embodiment, center electrical contact 220 of themating terminal connector 200 protrudes beyond inner surface 209 offlange 210 a corresponding distance such that when the terminalconnector 200 is threadedly engaged with ferrule 200, the rotation ofthe connector 200 on ferrule 110 is stopped by contact between the outerend 136 of the terminal pin 130 and center electrical contact 220 of theterminal connector 200. The distance which center electrical contact 220protrudes beyond inner surface 209 of flange 210 is preferably at leastabout 0.020 inches greater than the distance that outer end 136 isrecessed beneath the plane defined by the outer end 118 of ferrule 110.In this manner, substantially the same effective electrical contact isprovided between the end 136 of the terminal pin 130 and the centerelectrical contact 220 as is provided in the previously describedembodiment.

It will be apparent that although the attainment of effective electricalcontact between the terminal pin 130 of the cell's terminal assembly 100and the center electrical contact 220 of the mating terminal connector200 has been illustrated with reference to the embodiment of FIG. 4,these principles are equally applicable to the embodiments of FIGS. 7,8, and 9.

To facilitate connection of the cell's terminal assembly to an externaldevice to be powered by the cell, the mating terminal connectorpreferably further comprises a first conductor extending from the centerterminal through the flange of the cap, and a second conductor extendingfrom the perimeter terminal through the flange of the cap. FIG. 5 is atop view of the mating terminal connector 200 of FIGS. 1, 2, 4, and 4A,depicting such conductors provided for connection to a device to bepowered by a cell. FIG. 6 is a side cross-sectional view of the terminalconnector 200 of FIG. 2 and FIG. 5, taken along line 6-6 of FIG. 5.

Referring in particular to FIGS. 4, 5, and 6, center contact 220 isjoined to first conductor 250, which comprises an elongated horizontalbar 252 that extends from an upper edge 222 of center contact 220, anelbow 253, and an elongated vertical tab 254. The majority of elongatedhorizontal bar 252 is embedded within flange 216 of cap 210, with ashort section protruding from flange 216 proximate to elbow 253. In thepreferred embodiment, center contact 220 and first conductor 250 areintegrally formed as a single piece, and insert molded into the desiredposition when cap 210 is formed. Cap 210 is preferably made of aninjection moldable or curable polymer, such as polysulfone,polyetheretherketone, or polyurethane.

Perimeter contact 230 is joined to second conductor 260, which comprisesa short vertical section 261 that extends from an upper edge 248 ofperimeter contact 230, an elongated horizontal bar 262, an elbow 263(see also FIG. 1), and an elongated vertical tab 264. The majority ofelongated horizontal bar 262 is embedded within flange 216 of cap 210,with a short section protruding from flange 216 proximate to elbow 263.In the preferred embodiment, perimeter contact 230 and second conductor260 are also integrally formed as a single piece, and insert molded intothe desired position when cap 210 is formed.

The elongated tabs 254 and 264 of the first and second conductors 250and 260 are adapted for connection into an electrical receptacle (notshown). The electrical receptacle typically is comprised of a pair ofslots in a circuit board dimensioned so as to permit the elongated tabsof the conductors to be “plugged” into them. The center contact 220, theperimeter contact 230, and the electrical conductors 250 and 260 of themating terminal connector may be made of stainless steel or titanium, orother suitable metals are described previously herein for the ferrule110 and the terminal pin 130.

The embodiments described herein may be used with a variety of cells. Ingeneral, such a cell is comprised of a conductive casing closed at oneend and having an opening at the opposite end thereof closed by aconductive lid. The conductive lid is comprised of a wall having aninside surface, an outside surface, and an opening therethrough from theinside surface to the outside surface to which the cell's terminalassembly is joined and sealed; an electrode assembly housed inside thecasing and comprised of a first electrode of a first polarity includinga currant collector and a second electrode of a second, oppositepolarity. The current collector includes a coupling element forconnection to the terminal pin. The open volume within the conductivecasing is filled with an electrolyte to activate the electrode assembly.

The cell may be configured with a case-negative or case-positive groundconfiguration. The cell may be comprised of a simple sandwich-likerectilinear electrode structure, such as is disclosed in theaforementioned U.S. Pat. No. 5,250,373 to Muffoletto et al.Alternatively, the electrodes may be configured in a jellyrollarrangement, such as is disclosed in U.S. Pat. No. 6,951,576 toTakeuchi, which is assigned to the assignee of the present invention andincorporated herein by reference. In another embodiment, the electrodesmay be configured in a serpentine arrangement such as is disclosed inthe aforementioned U.S. Pat. No. 6,929,881 to Wutz et al. In a cell inwhich the electrodes are configured in a serpentine arrangement, thecell may further comprise a cathode bridge to facilitate connection of acurrent collector to the multiple cathode plates of the cell, as isdisclosed in the aforementioned U.S. Pat. No. 6,004,692 to Muffoletto etal. It is to be understood that these suitable cell configurations areto be considered as exemplary and not limiting, and that the terminalconnectors may be adapted to many other cell configurations.

FIG. 4A is a side cross-sectional view of a cell that is an alternativeto the cell of FIG. 4. The cell 10 includes a terminal assemblyconnected to the mating terminal connector 200 also depicted in FIG. 4.Terminal pin 131 differs from terminal pin 130 of the cell of FIG. 4, inthat it includes an elbow 133 proximate to the inner end 135 thereof.This feature aligns the inner section 137 of the terminal pin 131 withthe coupling element 43 of current collector 40, thereby providing agreater length of contact between the terminal pin 131 and currentcollector 40 at which a bond may be formed. An example of such aterminal pin and current collector configuration and bond is provided inthe aforementioned U.S. Pat. No. 5,250,373 to Muffoletto et al.

It is, therefore, apparent that there has been provided, in accordancewith the present invention, a coaxial electrical connector fitting forconnection to a cell used in implantable medical devices. While thisinvention has been described in conjunction with preferred embodimentsthereof, it is evident that many alternatives, modifications, andvariations will be apparent to those skilled in the art. Accordingly, itis intended to embrace all such alternatives, modifications andvariations that fall within the spirit and broad scope of the appendedclaims.

1. An electrochemical cell comprising a conductive lid comprised of awall having an inside surface, an outside surface, and an openingtherethrough from the inside surface to the outside surface, the cellcomprising: a) a ferrule comprised of a conductive hollow body, aninterior surface, an exterior surface, an outer end, and an inner end,the ferrule being electrically joined and sealed within the openingthrough the wall of the conductive lid; b) a conductive terminal pincomprising an elongated surface, an inner end, and an outer end, theterminal pin disposed within the hollow body of the ferrule, therebyforming an annular cavity between the elongated surface of the terminalpin and the interior surface of the ferrule; c) a hermetic seal formedin the annular cavity between the terminal pin and the interior surfaceof the ferrule; d) a terminal connector mated with the ferrule and theterminal pin, the terminal connector comprising a non-conductive bodyincluding a flange, a center terminal embedded in the flange, and aperimeter terminal disposed within the body of the terminal connector;and e) wherein with the terminal connector mated to the ferrule, theexterior surface of the ferrule is in contact with the perimeterterminal of the terminal connector and the terminal pin is in contactwith the center terminal of the terminal connector.
 2. The cell of claim1 wherein the ferrule is welded to the wall of the conductive lid withthe outer end of the ferrule extending outwardly beyond the outersurface of the lid.
 3. The electrochemical cell of claim 1 wherein theconductive hollow body of the ferrule is cylindrical having a centralaxis and the terminal pin is disposed within the cylindrical ferrulealigned along the central axis thereof.
 4. The cell of claim 3 whereinthe exterior surface of the ferrule is threaded to enable connectionwith corresponding threads of the terminal connector.
 5. The cell ofclaim 1 wherein the exterior surface of the ferrule is provided withprotruding pins to enable connection with a BNC structure of theterminal connector.
 6. The cell of claim 1 wherein the conductive lid,the ferrule, and the terminal pin are of either titanium or stainlesssteel.
 7. The cell of claim 1 wherein the terminal pin is made ofmolybdenum.
 8. An electrochemical cell comprising a conductive lidcomprised of a wall having an inside surface, an outside surface, and anopening therethrough from the inside surface to the outside surface, thecell comprising: a) a ferrule comprised of a conductive hollowcylindrical body having a central axis, an interior surface, an exteriorsurface, an outer end, and an inner end, the ferrule being electricallyjoined and sealed within the opening through the wall of the conductivelid; b) a conductive terminal pin comprising an elongated surface, aninner end, and an outer end, the terminal pin disposed within the hollowcylindrical body of the ferrule and aligned along the central axisthereof, thereby forming an annular cavity between the elongated surfaceof the terminal pin and the interior surface of the ferrule; c) ahermetic seal formed in the annular cavity between the terminal pin andthe interior surface of the ferrule; d) a terminal connector connectedto the ferrule and the conductive terminal pin, the terminal connectorcomprising a non-conductive cap including a hollow cylindrical bodycovered at an outer end by a flange, a center terminal embedded in theflange, and a perimeter terminal disposed within the hollow cylindricalbody of the cap; and e) wherein with the terminal connector connected tothe ferrule, the exterior surface of the ferrule is in contact with theperimeter terminal of the terminal connector, and the terminal pin is incontact with the center terminal of the terminal connector.
 9. The cellof claim 8 wherein the exterior surface of the ferrule is threaded, andthe perimeter terminal of the terminal connector is correspondinglythreaded to enable a threaded connection between the terminal connectorand the ferrule.
 10. The cell of claim 8 wherein the exterior surface ofthe ferrule is provided with protruding pins and the terminal connectoris formed as a BNC connector adapted to engage with the protruding pinsof the ferrule.
 11. The cell of claim 8 wherein the perimeter terminalof the terminal connector is press-fittingly engaged with the exteriorsurface of the ferrule.
 12. The cell of claim 8 wherein the perimeterterminal of the terminal connector is joined to the exterior surface ofthe ferrule by a weld.
 13. The cell of claim 12 wherein the cap of theterminal connector is made of ceramic.
 14. The cell of claim 8 whereinthe terminal connector further comprises a first conductor extendingfrom the center terminal through the flange of the cap and a secondconductor extending from the perimeter terminal through the flange ofthe cap.
 15. The cell of claim 14 wherein the first and secondconductors are comprised of elongated tabs adapted for connection intoan electrical receptacle.
 16. The cell of claim 8 wherein the conductivelid, the ferrule, the terminal pin, the center contact, and theperimeter contact are of either titanium or stainless steel.
 17. Thecell of claim 8 wherein the terminal pin is made of molybdenum.
 18. Theelectrochemical cell of claim 8 wherein the inner end of the ferrule iselectrically sealed to the lid and substantially coplanar with the innersurface of the conductive lid.
 19. An electrochemical cell comprising:a) a conductive casing having an opening at one end closed by aconductive lid, the conductive lid comprised of a wall having an insidesurface, an outside surface, and an opening therethrough from the insidesurface to the outside surface; b) an electrode assembly housed insidethe casing and comprised of a first electrode of a first polarity, asecond electrode of a second, opposite polarity, and a current collectorcomprising the first electrode; c) an electrolyte provided in the casingto activate the electrode assembly; d) a ferrule comprised of aconductive hollow body, an interior surface, an exterior surface, anouter end, and an inner end, the ferrule being electrically joined andsealed within the opening through the wall of the conductive lid; e) aconductive terminal pin comprising an elongated surface, an inner endelectrically connected to the current collector, and an outer end, theterminal pin disposed within the hollow body of the ferrule, therebyforming an annular cavity between the elongated surface of the terminalpin and the interior surface of the ferrule; f) a hermetic sealingmaterial formed in the annular cavity between the terminal pin and theinterior surface of the ferrule; g) a terminal connector mated to theferrule and the conductive terminal pin, the terminal connectorcomprising a non-conductive body including a flange, a center terminalembedded in the flange, and a perimeter terminal disposed within thebody of the connector; and h) wherein with the terminal connector matedto the ferrule, the exterior surface of the ferrule is in contact withthe perimeter terminal of the terminal connector and the terminal pin isin contact with the center terminal of the terminal connector.
 20. Theelectrochemical cell of claim 19 wherein the exterior surface of theferrule is threaded, and the perimeter terminal of the terminalconnector is correspondingly threaded to enable a threaded connectionbetween the terminal connector and the ferrule.
 21. The electrochemicalcell of claim 19 wherein the exterior surface of the ferrule is providedwith protruding pins and the terminal connector is formed as a BNCconnector adapted to engage with the protruding pins of the ferrule. 22.The electrochemical cell of claim 19 wherein the perimeter terminal ofthe terminal connector is press-fittingly engaged with the exteriorsurface of the ferrule.
 23. The electrochemical cell of claim 19 whereinthe perimeter terminal of the terminal connector is joined to theexterior surface of the ferrule by a weld.
 24. The electrochemical cellof claim 23 wherein the cap of the terminal connector is made ofceramic.
 25. The electrochemical cell of claim 19 wherein the terminalconnector further comprises a first conductor extending from the centerterminal through the flange of the cap and a second conductor extendingfrom the perimeter terminal through the flange of the cap.
 26. Theelectrochemical cell of claim 25 wherein the first and second conductorsare comprised of elongated tabs adapted for connection into anelectrical receptacle.
 27. The electrochemical cell of claim 19 whereinthe conductive lid, the ferrule, the terminal pin, the center contact,and the perimeter contact are of either titanium or stainless steel. 28.The electrochemical cell of claim 19 wherein the terminal pin is made ofmolybdenum.
 29. The electrochemical cell of claim 19 wherein theconductive hollow body of the ferrule is cylindrical having a centralaxis and the terminal pin is disposed within the cylindrical ferrulealigned along the central axis thereof.